US2981389A - Ratchet mechanism - Google Patents

Description

April 5, 1961 L. E. KILNESS 2,981,389

RATCHET MECHANISM Filed July 5, 1957 2 Sheets-Sheet l INVENTOR LUTHER E. N555 ATTORNEY5 April 1961 L. E. KILNESS 2,981,389

RATCHET MECHANISM Filed July 5, 1957 2 Sheets-Sheet 2 FIG. 8. a

. 70 FIG. l5. #7 my 67 ii ///Z/ Ill -l|llllllll H II INVENTOR LUTHEF E. K/L/VEZZS /Z7 2 BY ATTORNEY$ nited States Pawnt RATCHET MECHANISM Luther E. Kilness, Buffalo Gap, 5. Dak., assignor to The New Britain Machine Company Filed July 5, 195 7, Ser. No. 670,191

17 Claims. (Cl. 192- 45.1)

My invention relates to ratchet mechanisms, and has particular reference to ratchet wrenches. This invention incorporates improvements and refinements over the invention disclosed in my United States Patent No. 2,554,990.

It is an object of the invention to provide an improved device of the character indicated.

Another object is to provide an improved ratchet mechanism of such high strength that the ratchet head may be of a greatly reduced and compact size as compared to conventional ratchet devices of the same torque capacity;

It is also an object to provide an improved ratchet construction, characterized particularly by a greatly increased number of possible ratcheting positions, for a full rotation of the ratchet head thereof.

Still another object is to provide improved reverseactuating means in a ratchet mechanism of the character indicated.

A further object is to provide a reduction in parts and a simplification of individual parts in mechanisms of the character indicated.

A specific object is to meet the above objects with a reversible ratchet structure which may be palmed" without disturbing the selected direction of ratcheting engagement.

Other objects and various further features of novelty and invention will be pointed out or will occur to those skilled in the art from a reading of the following specification, in conjunction with the accompanying drawings. In said drawings which show, for illustrative purposes only, preferred forms of the invention:

Fig. 1 is a perspective view of a ratchet wrench of my invention;

Fig. 2 is an enlarged fragmentary view showing the head of the wrench of Fig. l, the working parts being shown in a predominantly vertical section, taken through the aXis of the wrench head;

Fig. 3 is a top view of the wrench head of Fig. 1, the actuating cover plate having been removed to more clearly reveal the operative parts;

Fig. 4 is a partly broken-away view similar to Fig. 3, but showing the parts in a reversed position;

I Fig. 5 is an enlarged fragmentary detail illustrating coaction between ratcheting parts within the wrench of Figs. 1 to 4;

Figs, 6 and 7 are simplified views generally similar to Fig. 4, but illustrating two further alternative shifting mechanisms of the invention;

Fig. 8 is a perspective view of an internal sub-assembly for a modified ratchet construction of the invention;

. Fig. 9 is a sectional view in the plane 9-9 of Fig. 8;

Fig. 10 is a view similar to Figs. 6 and 7, but showing another shifting mechanism;

Fig. 11 is a simplified view showing an alternative spring construction for operating the pawl of my mecha-' msm;

Fig. 12 is a side-elevation view, partly broken-away 2,981,389 Patented Apr. 25, 1961 and shown in section to illustrate an alternative for the arrangement of Fig. 11;

Fig. 13 is an enlarged side elevation of the spring of Fig. 12;

Fig. 14 is an enlarged side-elevation view, partly brokenaway and shown in section to illustrate the toggle-spring construction usable in the shift mechanism for the forms of Figs. 1-5, 6, 7, 8-9 and 10;

Fig. 15 is a view similar to Figs. 12 and 14, showing a further modified shift-spring construction, specifically applicable to the arrangement of Figs. 8-9;

Fig. 16 is a perspective view similar to Fig. 8, but illustrating another form of the invention;

Fig. 17 is a plan view of the work-turning member to illustrate a still further modification; and

Fig. 18 is an enlarged fragmentary sectional view taken in the plane 1818 of Fig. 17.

Briefly stated, my invention contemplates an improved ratchet-wrench construction wherein simplified operating mechanism determines the position and action of the pawl with reference to the ratchet piece of the driving member, the improvements being particularly directed to the general type of ratchet mechanism disclosed and claimed in said patent. In such mechanism, a driving member is provided with a cylindrical opening having inwardly extending teeth, and a work-turning member is rotatably mounted in the cylindrical opening. The turning member has a recess offset from the center thereof, said recess defining a pocket-like opening at an enlarged angular location on one side of the work-turning member. A toothed pawl of smaller size than the recess is located within the recess.

The means of the present invention is concerned with always resiliently positioning the pawl to determine the desired direction and nature of the ratcheting action. Specifically, in accordance with my present invention, I provide means normally and continuously radially outwardly urging the pawl for constant contact with the teeth of the driving member; said resilient means also continuously urge the pawl predominantly to one angular side of the recess, so that driving abutment may be had with the adjacent wall of the recess to the exclusion of the opposite wall of the recess for any selected direction of ratcheting action. Various organizations of resilient positioning and control means will be shown and described, and various organizations of reverse-control mechanisms will also be described.

Referring to Figs. 1 to 5 of the drawing, my invention is show in application to a reversible ratchet wrench comprising a driving member 10 having an elongated shank 11 formed at the outer end thereof with an enlarged handle 12 for easy manual operation thereof. The driving member 10 is generally cylindrical and is provided with an internal cylindrical opening 13 within which a work-rotating member 14 is rotatably mounted. The work-rotating member 14 is shown in Fig. 2 to have a cylindrical bearing portion 15 riding a suitably formed counterbore in the driving member 10, and projecting downwardly from the body 24 of the work-turning member 14 is a work-engaging part or shank 16, which may be of standard square or other shape for engagement with socket-type tools, and which may be provided with detent means 17 for snap-action engagement with such tools (not shown).

Ratcheting direction is controlled by a selector knob 18, which serves as the cover cap or closure for the other open side of the driving member or head 10. The actuator 18 may be journalled in the driving member 10, as at the counterbore 19 and may be permanently held in place by snap-ring means 20 riding a groove 21 in the cap 18, and a groove 22 in the driving member 10. Integrally formed with the cap 18 is an actuator pin or lug portion 23- for driving engagement with reverse-selector mechanism to be described.

As indicated generally above, the work-turning member 14 includes a substantial body 24 contained within the driving member or head and, in reference to Fig. 5, it will be seen that at one angular sector of said body 24, said body is recessed or provided with a pocket 25 for accommodation of pawl means 26. Preferably, the pocket 25 comprises lateral limits or walls 27-28 which may be flat and generally radially directed with respect to the axis 29 of rotation of the member 14; however, in the form shown, the pocket 25 is shown to be arcuate, the limits 27-28 being substantially radially inclined with respect to the axis 29.

The pawl 26 contained within the pocket or recess 25 is of smaller dimensions than the pocket 25, so that it may have certain freedom for angular and radial play with respect to the lateral limits 2728 of the recess 25. However, for driving in any selected direction, direct abutment with a selected one of the limits 27-28 is necessary, and I therefore provide abutment surfaces 30-31 on the pawl 26, suitably contoured for distributed-load engagement at 30-31, depending upon the selected direction of ratcheting engagement. A plurality of teeth 32 are provided over the substantial arcuate span of the pawl 26. These teeth are of the same pitch as the teeth 33 on the inner wall or bore of the driving member or head 10.

In accordance with a feature of the invention, means continuously urge the pawl 26 radially outwardly for constant engagement at the teeth 32-33. In the form shown, such means includes a ball 34 riding the back 35 of the pawl 26, and continuously urged against the same by spring means 36 located within a short radical bore 37 in the work-turning member 14.

As explained generally above, it is a feature of my invention that control means are provided for selectively positioning a pawl 26 predominantly to one angular side of the recess 25, depending upon the desired direction of ratcheting engagement. Such control means may include a plate or other member 39 pivoted on the axis of the work-turning member 14, as, for example, on a reduced upwardly projecting stud portion 40 thereof. The control means 39 preferably includes abutment means cooperating with suitable abutment means on the pawl 26 to determine the desired positioning control. In the form shown, the cooperating abutment means takes the form of separate pins 41-42 projecting upwardly from the body of the pawl 26 and into the general plane of the control plate 39, for loose reception in slotted openings 43-44 in said'control plate 39. The angular relation between the abutment means represented by the slot 43 and pin 41 on the one hand, and the slot 44 and pin 42 on the other hand should be such as to allow angular freedom or play of the control plate 39 with respect to the pawl 26, as is evident in Fig. 3 by the clearance at 45. The slotted openings 43-44 should also be of relatively substantial width compared with the widths of pins 41-42, for the same reason, namely, to facilitate the desired angular play (or lost motion) between these parts. Furthermore, a radial clearance should at all times exist between the abutment means 41-43 on the one hand, and between the abutment means 42-44 on the other hand, so as to allow radially inward movement of the pawl, as necessary to back off from .a given tooth engagement with the driving member 1 0* when resetting for the next ratcheted tooth engagement, as will be understood.

Quite aside from the angular location of the pawl 26 by means of angular placement of the control means 39, I prefer to employ a resilient mechanism for assuring a reversibly directed'predominant angularly pre loaded relation of the control plate 39 with the abutment 4-1 or 42, depending on the selected direction of ratcheting engagement. The means for preloading the control plate 39 may be a spring in the nature of a toggle mechanism, shown as a simple coil spring 47 in Fig. 2. The turns of the spring 47 are preferably loosely retained within locating means carried by the work-turning member 14, and in the form shown, such locating means is a tapered pocket or recess 48 (which may be conical) in the upper end of the work-turning member 14, and located off the axis of rotation of said member 14. The spring 47 includes two upwardly extending arms 49-60, one (5%) of which is constantly located in a hole 51 in the control plate 39, and the other (49) of which passes through an arcuate slot 52 in control plate 39 for constant engagement at 53 with a shift plate 54. The shift plate 54, in turn, has an opening 55 constantly receiving the selector pin 23 carried by the closure cap 18. The described parts (carried by the work-turning member 14) may be held in assembled relation by means of a snap washer 56, fitted in a groove at the end of the stud 40.

To complete the assembly of parts shown in the form of Figs. 1 to 5, I provide a peripheral seal member 57 between the topside of the driving member 10 and an overhanging lip of the cap 18. A second seal member 58 protects against entrance of dirt, dust and the like at the bearing 15 between the work-turning member 14 and the head 10, and snap-ring means 59 in a groove 60 serves to retain all parts in assembled relation.

For the relationship of parts shown in Figs. 2 and 3, the cover cap or selector member 18 has been rotated clockwise in the sense of Fig. 1, that is, as viewed from the top and looking down on the work. This has served to position the arm 49 of spring 47 in a direction up-out of the plane of Fig. 2, and, by reaction, has shifted the control plate 39 counterclockwise in the sense of Fig. 3. Thus, in achieving the selected position shown in Figs. 2 and 3, the selector plate 54 was subjected to clockwise rotation, and because of the reversing action of the toggle spring 47, the control plate 39 was subjected to counterclockwise rotation. It will be noted that the angular movement of plate 54 exceeds that of plate 39 so that, in effecting any reversing shift, the spring arm 49 may be carried past the instantaneous dead-center position of arm 50, thereby causing toggle action as well as reactive shifting of the control plate 39.

The clearance of the spring arms 49--50 within the retaining means 48 is preferably such that when shifted into the position shown, there is still some residual freedom for the arm 50 to move and thus continuously load the slot 43 against the pin 41, as shown in Figure 3. Thus, for the selected position shown, the pawl 26 is continuously loaded for abutment of surface 31 against recess wall 28. This means that for actuation of handle 12 in the counterclockwise direction, the tooth engagement at 3233 will be such as to drive the pawl 26 firmly against abutments 31-28, thus driving the work carried by the work rotating means 14 in a counterclockwise direction.

It will be noted that for the selected position shown in Figs. 2, 3 and 5, in which the selector member 18 has been shifted clockwise, the selected direction of driving engagement is counterclockwise. This means that if in order to get a better purchase or leverage on the work, the operator should palm the wrench head (meaning that if he should apply his hand or full weight against the head cover 18) while driving the handle 12 counterclockwise, he will not have to worry about inadvertently reversibly shifting the selector member 18, because the reaction against this hand will always be in the right direction to maintain the selected direction of driving engagement. In order to ratchet for another engagement position, the handle 12 should be backed off by clockwise rotation. This means that the pawl 26 will no longer be driven againstgabutments 28 -31, but will be relieved from the same the pin 41 being resiliently held against the edge of slot opening 43 so as to avoid loss of control, but nevertheless having freedom to back off radially against the action of spring 36 in order to'permit the teeth 32-33 to ride up and over each other for back ratcheting; the relative positioning of pawl 26 and of the members -14 during a back-ratcheting operation is suggested by dashed outlines in Fig. 5. When the handle 12 is next driven counterclockwise, the firm driving relation is again achieved.

For reversed action, as for the case when the selector member or cover plate 19 is shifted counterclockwise, the selector plate 54 will have been similarly shifted counterlockwise as shown in Fig. 4. This will have involved shifting the arm 49 of spring 47 past the dead center toggle position, so that the control plate 39 is reactively shifted clockwise, for engagement of the edge of slot 44 with pin 42, and for corresponding release of slot 43 from pin 41. For this selected position of the parts, the wrench is set for driving when the crank arm 12 is actuated clockwise and for back-ratcheting when the handle 12 is moved counterclockwise, as will be understood.

Fig. 6 illustrates a slight modification in which the control means for positioning the pawl and resiliently loading the same is merely formed of stiff wire or of stiff ribbon. The single piece of stiff material is shown at 65 to be folded at its middle, defining a loop at 66 whereby the spring arm 49 may be continuously engaged. The central part of the folded member 65 is bowed at 67 to define a hub for pivotal bearing support on the stud portion 40, and separate forked legs 68-69 provide the function described in Fig. 3 for the adjacent side walls or edges of slot 43-44. The forked legs 68-69 thus are poised for selective abutment withthe pin 41 or with the pin 42 on pawl 26, but with angular freedom for the purposes discussed above. Operation is otherwise as described for Figs. 1 to 5, in that the same toggle-spring action described at 47 .(and control means for positioning the same) .may be employed, the only difference being that the shift plate for actuating the toggle spring 47 in Fig. 6 should engage the outer arm 50 thereof, rather than the inner, arm, because, of course, it is not convenient to provide an elongated slot opening in member 65 analogous to the slot opening 52 in the selector plate 39 of Fig. 3.

The arrangement of Fig. 7 functionally duplicates that described for Fig. 6, the essential difference being that in place of the stiff ribbon or wire 65, I employ a stamped sheet-metal control part 70 performing substantially the same functions. The control means 70 has a central opening pivotally mounted on the stud 40 and is provided with an aperture at 71 for receiving an arm of the togglespring 47 (not shown in Fig. 7). The abutment mechanism whereby the outer end of the control means 70 engages the pawl 72 is slightly different from that describedpreviously, in that upwardly extending shoulders 73-74 are integrally formed at the lateral limits of the pawl 72. Said shoulders are provided with generally inwardly converging surfaces on which opposed ears 75-76 of the control means 70 may ride, depending upon the selected position thereof.- Operation is otherwise as described previously.

In the arrangement of Figs. 8 and 9, the driven parts of the ratchet-head assemblyare shown prior to insertion within the driving member or head 10. The pawl itself is identified at 78, and is again received within a recess or pocket 79 on the main body 80 of the workturning member. An arcuate groove 77 formed in the pawl 78, and having its counterpart in a peripherally extending groove 81 in the remainder of the body 80, servesto retain an actuating member or shift ring 82. Said actuating member is characterized by overlapped endsat 83 having registering openings at 84 for engagement by one of the arms of a toggle spring (not shown) within retaining pocket 48. The fit of the ring 82 in the groove 81 is preferably loose and relatively frictionfree. The ring 82 includes radially inwardly extending means 85 for loose, angular-locating engagement with a suitably formed recess 86 in the groove 77 of the pawl 78. It will be seen that the ring 82 provides a control means for selectively determining the particular predominant side of the recess 79, into which pawl 78 is to be shifted, and against which pawl 78 is to be resiliently urged. Operation is thus otherwise as previously described.

The arrangement of Fig. 10 illustrates a still further alternative control means. All previous control means, such as the plate 39 in Figs. 2 and 3, the stiff bent member 65 of Fig. 6, the plate 70 of Fig. 7, and the ring 82 of Figs. 8 and 9, develop their action essentially concentrically with respect to the axis of the work-turning member. In Fig. 10, however, the pivotal action of control means 90 is about a pivot 91, radially offset from the axis of the work-turning member 92, and preferably diametrically opposite the location of the pawl recess 93. In this case, therefore, the stud 40 on the workturning member may serve merely for determining limits of lateral motion for the control means 90, as by permitting freedom for movement at an arcuate or otherwise elongated slot 94. Projecting ears -96 provide the abutment means for engagement with pins 41-42 of the pawl 26, as will be understood. Actuating toggle-spring engagement with the control means 90 may be developed at a first localized opening 97, at which the short arm of the toggle spring may be received; the long arm may pass through an elongated slot 98, whereby engagement thereof with the selector plate (corresponding to plate 54, of Fig. 2) may be developed.

Fig. 11 illustrates an alternative mechanism whereby the pawl 26 may be continuously radially outwardly urged. In the arrangement of Fig. 7, the spring means 36 is contained within a locating pocket or bore 37' in the pawl 26', and for smooth action, a ball 34 rides the inner portion of the pawl recess 25 on the work-turning member 14. Action is as described at 26-34-36 in Fig. 5.

In the arrangement of Figs. 12 and 13, a simple V-type spring member is formed with oppositely extending actuating arms 101-102, and is preloaded by direct compression between a socket 103 (for arm 102 in the pawl recess 104 of the work-turning member 105) and a similar socket 106 (for arm 101, at a central location on the back side of the pawl 107).

Fig. 14 merely illustrates in simplified detail the nature of support of the toggle spring 47 in the tapered retaining socket 48, all as previously described. The main point to observe is that the retaining socket 48 lends itself to the proper support of the spring 47 whether the long arm 49 or the short arm 50 is in the radially outer position or in the radially inner position, as dictated by the requirements of actuation in accordance with the various arrangements (of Figs. 1-5, 6, 7, 8-9, and 10) for operating the control means for the pawl.

Fig. 15 illustrates a modified form of toggle spring in specific application to the arrangement of Figs. 8 and 9. The spring 110 is' of generally Z-shape having a leg 111 received in the registering openings 84 of the shift ring 82, and having another leg 112 received in a suitable actuating pin 113 carried by or forming part of the selector plate 54 (not shown), as will be understood.

In the arrangement of Fig. 16, the control means 115 is shown as a plate having similar opposed sets of notches 43-44 and 43'-44, for coaction with the pins 41-42 of a first pawl 26 and with the pins 41-42 of a second diametrically opposed pawl 26'. Each of the pawls 26-26 is received in similar diametrically opposed recesses (not shown) but in a manner completely analogous to that described for the single recess 25 shown in enlarged detail in Fig. 5; similar dual-pawl structures have 75 been shown in my said patent, and therefore, further detail is not considered necessary in the present description. Fig. 16 further illustrates an alternative toggle spring 116 of generally hairpin shape, and having one lower offset arm or end 117 engaged in a suitable socket on the control means 115, and upper offset arm or end 118 engageable with the cover plate or control member 119, as between closely spaced locating pins 120, depending from member 119. Further locating pins 121-122 are fixedly carried by the work-turning member 123, and provide means (projecting through an elongated arcuate slot 124 in control means 115) whereby limits to angular play of the top arm 118 of the spring 116 are determined. In operation, the selected position of cover 119 will determine whether the spring 116 is laid generally against the limit-stop or post 122 as shown, or is flipped over and laid against the opposite limiting post 121. The operation is otherwise as described for the preceding figures.

In the arrangement of Figs. 17 and 18, I merely illustrate that the socket which locates the toggle spring (such as the spring 47 of Figs. 2 and 3) need not be a tapered conical bore; thus, for the situation in which the work-turning member 125 is a die-casting, it may be desirable to provide a socket 126 of converging generally trapezoidal section, having substantially flat flared walls 127-128, as shown.

It will be seen that I have described an improved ratchet mechanism featuring simplicity of control or ganlzations, and ease of action and control. The control has been found to be extremely reliable and fool-proof and lends itself to incorporation in a well-sealed assembly. The particular virtue of ratchets of the present character is that they lend themselves to provision of very large numbers of teeth in the bore of the driving member so that a very much greater number of possible ratcheting positions is available. Furthermore, for any driving engagement at a given ratchet position, all teeth of the pawl develop full contact with the teeth of the driving member, so that extensive arcuate distribution of the load is achieved.

Wh.le I have described my invention in detail for the preferred forms shown, it will be understood that modification may be made within the scope of the invention as defined in the claims which follow.

I claim:

1. In a ratchet mechanism, the combination of a driving member having a cylindrical opening with a plurality of inwardly extending teeth, distributed around said opening, a work-turning member rotatably mounted in the cylindrical opening, said Work-turning member having a recess at the periphery with at least two angularly spaced sides, a toothed pawl contained by the recess and of smaller size than the recess to permit radial withdrawal of the pawl from the teeth in the cylindrical opening, a control member pivotally mounted with respect to said work-turning member and having abutment means cooperating with said pawl for locating said pawl in a selected position predominantly to one angular side of said recess adjacent the nearby side wall of said recess and spaced from the opposite side wall of said recess, and spring means reacting between said Work-turning member and said control member, and resiliently urging the same in said predominant direction.

2. The ratchet mechanism of claim 1, and including means for shifting the direction of action of said spring means, whereby said control member is shifted to urge said pawl in the predominant direction toward the other side of said recess.

3. In a ratchet mechanism, the combination of a driving member having a cylindrical opening with a plurality of inwardly extending teeth, distributed around the opening, a work-turning member rotatably mounted in the cylindrical opening, said work-turning member having a recess at one predominant angular location thereon'adjacent the periphery to define two opposite lateral walls, a

toothed pawl retained by said opening and of smaller size than said recess, means resiliently urging said pawl radially outwardly for continuous toothed engagement with said driving member, and means including a toggle mechanism reacting between said work-turning member and said pawl, and having a dead-center position effectively intermediate a first position controlling the placement of said pawl predominantly adjacent one lateral wall of said recess, and a second position controlling the placement of said pawl predominantly adjacent the opposite lateral wall of said recess.

4. The ratchet mechanism of claim 3, and including means for selectively operating said toggle mechanism.

5. In a ratchet mechanism, the combination of a driving member having a cylindrical opening with a plurality of inwardly directed teeth distributed around the opening, a work-turning member rotatably mounted in the cylindrical opening and having a recess on one side thereof facing said teeth and defining spaced apart side walls, a toothed pawl retained by said recess and of smaller size than said recess and bodily laterally movable in said recess, resilient means continuously urging said pawl for engagement at said teeth with said driving member and laterally urging said pawl in a predominant angular direction for positioning the same predominantly on one side of said recess with one end of said pawl adjacent the nearby side wall of said recess and spaced from the other side wall of said recess, selectively operable means for reversing the laterally urged direction of said pawl, whereby on operation of said last-defined means said pawl may be shifted so that the other end of said pawl is adjacent the other wall of said recess and is spaced from the side one wall of said recess, and said resilient means comprising first spring means constantly urging said pawl radially outwardly, and second reversible operable spring means operated by said selectively operable means.

'6. Mechanism according to claim 5, in which said first spring means comprises a coil spring located in a radial bore in said work-turning member and communicating with said recess.

7. Mechanism according to claim 5, in which said first spring means comprises a coil spring located in a radial bore in said pawl and communicating with said recess.

8. Mechanism according to claim 1, in which said control member comprises an angularly shiftable element pivotally carried by said work-turning member and including means angularly engageable with said pawl with angular lost motion, said element positioning said pawl adjacent one side of said recess when driven to one lost motion limit and positioning said pawl adjacent the other side of said recess when driven to the other lost-motion limit.

9. Mechanism according to claim 8, in which said element is pivoted on the axis of said work-turning member.

10. Mechanism according to claim 8, in which said element is pivoted off the axis of said work-turning member and on the side thereof opposite said recess.

11. Mechanism according to claim 8, in which said element is a plate.

12. Mechanism according to claim 8, in which said element is formed of an elongated bent strip of stilt material.

13. In a ratchet mechanism, the combination of a driving member having a cylindrical opening with a plurality of inwardly extending teeth distributed around said opening, a work-turning member rotatably mounted in the cylindrical opening, said work-turning member having a recess adjacent said teeth and with spaced walls, a toothed pawl having an abutment surface and contained by the recess and of smaller size than the recess to permit withdrawal of the pawl from the teeth in the cylindrical opening, and means for holding the pawl in ratcheting engagement with the teeth in said opening, the last-named means including a control member having an abutment surface cooperable with said abutment surface of the pawl located near one end of the pawl for holding the pawl adjacent to one side of the recess during the back stroke, the abutment surface of the pawl being slidable inwardly relative to the abutment surface of the control member as the pawl teeth emerge from full engagement.

14. In a ratchet mechanism, the combination of a driving member having a cylindrical opening with a plurality of inwardly extending teeth distributed around said opening, a work-turning member rotatably mounted in the cylindrical opening, said work-turning member having a recess adjacent said teeth and with spaced walls, a toothed pawl having an abutment surface and contained by the recess and of smaller size than the recess to permit withdrawal of the pawl from the teeth in the cylindrical opening, and means for holding the pawl in ratcheting engagement with the teeth in said opening, the lastnamed means including a resilient member acting between the pawl and the work-turning member for urging the pawl against the teeth in said opening and a control member having an abutment surface cooperable with said abutment surface of the pawl for holding the pawl adjacent to one side of the recess during the back stroke, the abutment surface of the pawl being slidable inwardly relative to the abutment surface of the control member as the pawl teeth emerge from full engagement.

15. In a ratchet mechanism, the combination of a driving member having a cylindrical opening with a plurality of inwardly extending teeth distributed around said opening, a work-turning member rotatably mounted in the cylindrical opening, said work-turning member having a recess extending between angularly spaced wall limits, a toothed pawl contained by the recess and having angularly spaced ends for selective abutment with the adjacent spaced limits of the recess, said pawl being of smaller size than the recess to permit radial withdrawal of the pawl from the teeth in the cylindrical opening, an angularly shiftable control element pivotally mounted with respect to said work-turning member and having abutment means engageable with said pawl with angular lost motion and near said ends for locating said pawl in a selected position predominantly to one angular side of said recess adjacent the nearby side wall of said recess and spaced from the opposite side wall of said recess, said element positioning said pawl adjacent one side of said recess when driven to one lost-motion limit and positioning said pawl adjacent the other side of said recess when driven to the other lost-motion limit, and spring means reacting between said driving member and said control element and resiliently urging the same in said predominant direction.

16. In a ratchet mechanism, the combination of a driving member having a cylindrical opening with a plurality of inwardly extending teeth distributed around said opening, a work-turning member rotatably mounted in the cylindrical opening, said work-turning member having a recess extending between angularly spaced wall limits, a toothed pawl contained by the recess and having angularly spaced ends for selective abutment with the adjacent spaced limits of the recess, said pawl being of smaller size than the recess to permit radial withdrawal of the pawl from the teeth in the cylindrical opening, an angularly shiftable control element pivotally mounted with respect to said work-turning member and having abutment means engageable with said pawl with angular lost motion and intermediate said ends for locating said pawl in a selected position predominantly to one angular side of said recess adjacent the nearby side wall of said recess and spaced from the opposite side wall of said recess, said element positioning said pawl adjacent one side of said recess when driven to one lost-motion limit and positioning said pawl adjacent the other side of said recess when driven to the other lost-motion limit, and spring means reacting between said driving member and said control element and resiliently urging the same in said predominant direction.

17. In a ratchet mechanism, the combination of a driving member having a cylindrical portion, said cylindrical portion having an opening, a work-turning member having a cylindrical portion rotatably mounted in said opening in the cylindrical portion of said driving member, a plurality of angularly spaced teeth extending radially on one of said members and facing the cylindrical portion of the other of said members, said other of said members having a localized recess of predetermined dimensions adjacent said teeth and having angularly spaced-apart abutment walls, a pawl fitted substantially within said localized recess and having angularly spaced-apart abutment surfaces to co-act selectively with said spaced-apart abutment walls, a toothed arc on said pawl, the teeth of said are being formed for engagement with said plurality of teeth, said pawl being smaller in dimensions than said predetermined dimensions of said localized recess to permit withdrawal of said toothed arc from the teeth on said one of the members and to permit lateral shifting of said pawlv within said recess, and means to position said pawl within said recess for ratchet engagement with the teeth on said one of the members, said last-named means including shiftable spring means to resiliently urge said pawl predominantly on one side of said recess with one of said abutment surfaces positioned to abut one of said abutment walls, said means to position said pawl within said recess also includes angularly shiftable control means connected with said spring means to shift said spring means laterally so that said pawl is urged resiliently into substantially abutting relationship with a selected one of said abutment walls.

References Cited in the file of this patent UNITED STATES PATENTS 1,995,009 Pfauser et al. Mar. 19, 1935 2,554,990 Kilness May 29, 1951 FOREIGN PATENTS 499,381 Canada Jan. 19, 1954

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